Throttle valve



1924. Oct L. SNEAD THROTTLE VALVE Filed April 13. 1923 I Patented Oct. 21, 1924.

UNITED STATES LESLIE SNEAD, 0F RICHMOND, VIRGINIA.

THROTTLE VALVE.

Application filedApi-il 13, 1923. Serial No. 631,860;

To all whom it may concern:

Be it known that I, LESLIE SNEAD, of Richmond, in the county of Henrico and State of Virginia, have invented a certain new and useful Improvement in Throttle Valves, of which improvement the followin' is a specification,

y invention relates to throttle valves of the double poppet type, and its object is to provide an appliance of such type which will enable the valve seats to be made of as large diameter as desired, and which will be held seated by a preponderance of pres sure sufficiently great to prevent accidental displacement, but so comparatively slight in degree as to enable the valve to be readily unseated, whenever desired, by the application of a small amount of power to its op erating lever.

The improvement claimed is hereinafter fully set forth.

In the accompanying drawing: Figure 1 .is a vertical section through a throttle valve and its accessories, embodying my invention, on the line a a of Fig. 2; Fig. 2, a horizontal section, on the line b b of Fig. 1; and, Fig. 3, a transverse section through the lower valve seat, detached.

In the practice of my invention, referring descriptively to the specific embodiment thereof which is herein exemplified, I provide a throttle valve, 3, of the double poppet type, which is fitted in a throttle box or casing, 1, formed integral with, or secured to, a stand pipe, 2, the lower end of which communicates, in the usual manner, with a steam supply or dry pipe, which does not form part of my present invention and therefore is not herein illustrated.

The throttle box, 1, is of approximately spherical form, and is open at its top, except when the throttle valve is seated, to

r the steam space of the boiler, and continuously open to the stand pipe, 2. A downwardly curved wall, 1, extends partially across the throttle box, and is connected thereto by radially extending ribs, 1", an, annular space, 1, for the passage of steam to the stand pipe, being interposed between the periphery of the wall, 1, and the wall of the throttle box.

The throttle valve is adapted to seat on a tapered valve face, formed in an upper valve seat, 4, which is fitted in the open to of the throttle box, and secured therein by olts, 5, and on a similar face, formed in a floating lower valve seat, 4, which is fitted, with a limited degree of movement in the axial line of the valve, in the wall, 1. The movement of the floating valve seat is limited by bolts, 6, screwed into the throttle box, and entering a peripheral groove, 4', in the seat. The valve face of the floating seat is slightly less in diameter than that of the fixed upper valve seat, 4, so as to institute 2. corresponding preponderance of downward pressure on the valve, which normally holds it seated, while not being sufliciently great to oppose any substantial resistance to unseating it when desired.

The throttle valve is moved to and from the valve faces in the seats, 4 and 4:, by any suitable known actuating mechanism, which does not form part of my invention.

In the operation of the appliance, the throttle valve is normally held seated by the preponderance of downward pressure upon it, but can be unseated without difficulty, by the operator. When the valve is unseated. steam from the boiler is thereby o.dmitted to the throttle box, and through the annular passage, 1, thereof, to the stand pipe and connected dry pipe. In the upward movement of the valve the floating valve seat follows it, through the slight range of movement permitted by the bolts, 6, after which, the areas of the upper and lower seating faces of the valve being equal, the valve becomes perfectly balanced, and thereafter can be moved to any desired degree in either direction, without any resistance being opposed to its movement.

It is well recognized, in locomotive practice, that a throttle valve should be so far unbalanced as to be normally held to its seat, by the action of a de ee of boiler pressure upon it, when seate sufficient to prevent it from being jarred, or otherwise accidentally moved, from its seat. To enable a throttle valve, so unbalanced, whether of the single or double poppet type, to be readily unseated by the engineman, when desired, it is ordinarily the practice to provide it with a so-called pilot valve, which is opened in and by the preliminary move ment of the throttle lever, and balances the from the prior practice above noted, by dis pensing with asupplemental preliminary or pilot valve, and the provision of a novel floating valve seat, which increases, to a sufficient extent, the area of admission of steam for balancing the throttle valve.' The resultant advanta e is a substantial one, in the avoidance 0% the expense and complication ofv a separate supplemental valve, and the quicker balancing action of the steam upon the throttle valve, than if supplied through a passage controlled by a supplemental valve.

It will be seen that, under my invention, a throttle valve can be made of an desired diameter, and that, by proper a justment of the relation of theidiameters of the valve faces of the fixed and the floating valve seats, the degree of unbalanced pressure b which the valve is normall may be caused to be that w ich is considered to be most desirable in practical service.

I claim as my invention and desire to secure by Letters Patent:

= 1. The combination, 'with a normally unheld seate balanced double poppet throttle valve, of means for relieving preponderance of pressure on said valve in its unseating movement, by increase of steam admission area to one of its seating faces.

2. The combination of a throttle box; a

normally unbalanced double poppet throttle that of the fixed seat; and a double (pop et throttle valve, adapted to seat on sai faces.

LESLIE SNEAD.

Witnesses:

Geo. E. Dorm, J. G. Danvn. 

